Syria will cede control of its chemical weapons to the international community, the country's president, Bashar al-Assad, has said in a yet-to-be-aired interview on Russian television.

In what is believed to be his first public acknowledgement of the country's chemical weapon stockpile, Interfax news agency quoted the president as saying the move had not been prompted by US military threats but Russian diplomatic efforts.

"Syria is placing its chemical weapons under international control because of Russia. The US threats did not influence the decision," Interfax said, quoting the state-run Rossiya-24 channel's yet-to-be-aired interview.

Assad also told Rossiya-24 that Syria would submit documents to the United Nations for an agreement governing the handover of its chemical arsenal.

The Russian president, Vladimir Putin, has said the initiative will not succeed unless Washington abandons plans for potential air strikes to punish Assad for a poison gas attack on 21 August that the US president, Barack Obama, blames on Syrian government forces.

Syria, which denies it was behind that attack, has agreed to Moscow's proposal that it give up its chemical weapons stocks – apparently averting what would have been the first direct western intervention in a war that has killed more than 100,000 people.

Kerry is accompanied by US chemical weapons experts to look at and possibly expand on Russian ideas for the complex task of dealing safely with the vast stockpiles in the midst of the brutal and unpredictable Syrian conflict. Russian technical experts will join Lavrov in the meetings.

"Our goal here is to test the seriousness of this proposal, to talk about the specifics of how this would get done, what are the mechanics of identifying, verifying, securing and ultimately destroying the chemical weapons," the state department said shortly before Kerry left Washington.

In his comment article for the New York Times published on Wednesday, Putin welcomed Obama's consideration of the Russian-backed plan for Syria to hand over its chemical weapons and said his relationship with the US president was marked by "growing trust".

But he warned: "It is alarming that military intervention in internal conflicts in foreign countries has become commonplace for the United States. Is it in America's long-term interest? I doubt it.

"Millions around the world increasingly see America not as a model of democracy but as relying solely on brute force, cobbling coalitions together under the slogan: 'You're either with us or against us.'" Putin said Russia was not aiming to protect the Syrian government but international law.

The White House said on Wednesday it was increasingly confident that its Kremlin partners were acting in good faith by "putting their prestige on the line".

"We have seen more co-operation from Russia in the last two days than we have heard in the last two years," said the White House spokesman Jay Carney.

"The proposal they have put forward is very specific and the Syrian reaction is a total about-face. This is significant."